md/raid1: Fix trailing semicolon

The trailing semicolon is an empty statement that does no operation.
Removing it since it doesn't do anything.
Signed-off-by: Luis de Bethencourt <luisbg@kernel.org>
Signed-off-by: Shaohua Li <sh.li@alibaba-inc.com>

drivers/md/raid1.c

@@ -1108,7 +1108,7 @@ static void alloc_behind_master_bio(struct r1bio *r1_bio,
 
 	bio_copy_data(behind_bio, bio);
 skip_copy:
-	r1_bio->behind_master_bio = behind_bio;;
+	r1_bio->behind_master_bio = behind_bio;
 	set_bit(R1BIO_BehindIO, &r1_bio->state);
 
 	return;